My stratergy is using heavy material, Just start with the 4 soldiers and gather 6 points.
With this points get a Jeep, wich is totally awesome it has a machine gun and it protects your soldiers. After this just wait for 20 pts and get a AAA, Put the AAA behind the Jeep and your soldiers, after that just wait some more and get a tank.
now you can get more advanced soldiers, like bazookas and spec ops. You also can get a engineer and get more defences but i dont like that.